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After spinal cord injury (SCI), infiltrating macrophages undergo excessive phagocytosis of myelin and cellular debris, forming lipid-laden foamy macrophages. To understand their role in the cellular pathology of SCI, investigation of the foamy macrophage phenotype in vitro revealed a pro-inflammatory profile, increased reactive oxygen species (ROS) production, and mitochondrial dysfunction. Bioinformatic analysis identified PI3K as a regulator of inflammation in foamy macrophages, and inhibition of this pathway decreased their lipid content, inflammatory cytokines, and ROS production. Macrophage-specific inhibition of PI3K using liposomes significantly decreased foamy macrophages at the injury site after a mid-thoracic contusive SCI in mice. RNA sequencing and in vitro analysis of foamy macrophages revealed increased autophagy and decreased phagocytosis after PI3K inhibition as potential mechanisms for reduced lipid accumulation. Together, our data suggest that the formation of pro-inflammatory foamy macrophages after SCI is due to the activation of PI3K signaling, which increases phagocytosis and decreases autophagy.
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Fosfatidilinositol 3-Quinases , Traumatismos da Medula Espinal , Camundongos , Animais , Fosfatidilinositol 3-Quinases/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Macrófagos/metabolismo , Traumatismos da Medula Espinal/metabolismo , Lipídeos , Medula Espinal/patologiaRESUMO
Axon injury is a hallmark of many neurodegenerative diseases, often resulting in neuronal cell death and functional impairment. Dual leucine zipper kinase (DLK) has emerged as a key mediator of this process. However, while DLK inhibition is robustly protective in a wide range of neurodegenerative disease models, it also inhibits axonal regeneration. Indeed, there are no genetic perturbations that are known to both improve long-term survival and promote regeneration. To identify such a neuroprotective target, we conducted a set of complementary high-throughput screens using a protein kinase inhibitor library in human stem cell-derived retinal ganglion cells (hRGCs). Overlapping compounds that promoted both neuroprotection and neurite outgrowth were bioinformatically deconvoluted to identify specific kinases that regulated neuronal death and axon regeneration. This work identified the role of germinal cell kinase four (GCK-IV) kinases in cell death and additionally revealed their unexpected activity in suppressing axon regeneration. Using an adeno-associated virus (AAV) approach, coupled with genome editing, we validated that GCK-IV kinase knockout improves neuronal survival, comparable to that of DLK knockout, while simultaneously promoting axon regeneration. Finally, we also found that GCK-IV kinase inhibition also prevented the attrition of RGCs in developing retinal organoid cultures without compromising axon outgrowth, addressing a major issue in the field of stem cell-derived retinas. Together, these results demonstrate a role for the GCK-IV kinases in dissociating the cell death and axonal outgrowth in neurons and their druggability provides for therapeutic options for neurodegenerative diseases.
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Axônios/enzimologia , Axônios/patologia , Sistema Nervoso Central/patologia , Quinases do Centro Germinativo/metabolismo , Regeneração Nervosa , Animais , Sequência de Bases , Sistemas CRISPR-Cas/genética , Morte Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Dependovirus/metabolismo , Modelos Animais de Doenças , Humanos , Camundongos Endogâmicos C57BL , Regeneração Nervosa/efeitos dos fármacos , Crescimento Neuronal/efeitos dos fármacos , Traumatismos do Nervo Óptico/metabolismo , Traumatismos do Nervo Óptico/patologia , Organoides/metabolismo , Inibidores de Proteínas Quinases/farmacologia , Células Ganglionares da Retina/efeitos dos fármacos , Células Ganglionares da Retina/metabolismo , Transdução de Sinais/efeitos dos fármacosRESUMO
Advances in the understanding of lipid droplet biology have revealed essential roles for these organelles in mediating proper cellular homeostasis and stress response. Lipid droplets were initially thought to play a passive role in energy storage. However, recent studies demonstrate that they have substantially broader functions, including protection from reactive oxygen species, endoplasmic reticulum stress, and lipotoxicity. Dysregulation of lipid droplet homeostasis is associated with various pathologies spanning neurological, metabolic, cardiovascular, oncological, and renal diseases. This review provides an overview of the current understanding of lipid droplet biology in both health and disease.
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Gotículas Lipídicas , Metabolismo dos Lipídeos , Estresse do Retículo Endoplasmático , Homeostase , Gotículas Lipídicas/metabolismo , Metabolismo dos Lipídeos/fisiologiaRESUMO
Tissue damage after spinal cord injury (SCI) elicits a robust inflammatory cascade that fails to resolve in a timely manner, resulting in impaired wound healing and cellular regeneration. This inflammatory response is partly mediated by infiltrating immune cells, including macrophages. As professional phagocytes, macrophages initially play an important role in debris clearance at the injury site, which would be necessary for proper tissue regeneration. After SCI, most macrophages become filled with lipid droplets due to excessive uptake of lipid debris, assuming a "foamy" phenotype that is associated with a proinflammatory state. Myelin has been assumed to be the main source of lipid that induces foamy macrophage formation after injury given its abundance in the spinal cord. This assumption has led to the widespread use of purified myelin treatment to model foamy macrophage formation in vitro. However, the assumption that myelin is necessary for foamy macrophage formation remains untested. To this end, we developed a novel foamy macrophage assay utilizing total spinal cord homogenate to include all sources of lipid present at the injury site. Using the myelin basic protein knockout (MBP KO, i.e., Shiverer) mice that lack myelin, we investigated lipid accumulation in foamy macrophages. Primary macrophages treated with myelin-deficient spinal cord homogenate still formed large lipid droplets typically observed in foamy macrophages, although to a lesser degree than cells treated with normal homogenate. Similarly, MBP KO mice subjected to contusive spinal cord injury also formed foamy macrophages that exhibited reduced lipid content and associated with improved histological outcomes and reduced immune cell infiltration. Therefore, the absence of myelin does not preclude foamy macrophage formation, indicating that myelin is not the only major source of lipid that contributes this pathology, even though myelin may alter certain aspects of its inflammatory profile.
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Macrófagos/patologia , Bainha de Mielina/patologia , Traumatismos da Medula Espinal/patologia , Medula Espinal/patologia , Animais , Citocinas/metabolismo , Modelos Animais de Doenças , Feminino , Inflamação/metabolismo , Inflamação/patologia , Lipídeos , Ativação de Macrófagos/fisiologia , Macrófagos/metabolismo , Masculino , Camundongos , Bainha de Mielina/metabolismo , Medula Espinal/metabolismo , Traumatismos da Medula Espinal/metabolismoRESUMO
We describe the assembly and annotation of a chemogenomic set of protein kinase inhibitors as an open science resource for studying kinase biology. The set only includes inhibitors that show potent kinase inhibition and a narrow spectrum of activity when screened across a large panel of kinase biochemical assays. Currently, the set contains 187 inhibitors that cover 215 human kinases. The kinase chemogenomic set (KCGS), current Version 1.0, is the most highly annotated set of selective kinase inhibitors available to researchers for use in cell-based screens.
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Descoberta de Drogas , Inibidores de Proteínas Quinases/química , Proteínas Serina-Treonina Quinases/química , Bibliotecas de Moléculas Pequenas/química , Humanos , Inibidores de Proteínas Quinases/uso terapêutico , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Bibliotecas de Moléculas Pequenas/uso terapêutico , Relação Estrutura-AtividadeRESUMO
Histone deacetylase (HDAC) inhibitors may have therapeutic utility in multiple neurological and psychiatric disorders, but the underlying mechanisms remain unclear. Here, we identify BRD4, a BET bromodomain reader of acetyl-lysine histones, as an essential component involved in potentiated expression of brain-derived neurotrophic factor (BDNF) and memory following HDAC inhibition. In in vitro studies, we reveal that pharmacological inhibition of BRD4 reversed the increase in BDNF mRNA induced by the class I/IIb HDAC inhibitor suberoylanilide hydroxamic acid (SAHA). Knock-down of HDAC2 and HDAC3, but not other HDACs, increased BDNF mRNA expression, whereas knock-down of BRD4 blocked these effects. Using dCas9-BRD4, locus-specific targeting of BRD4 to the BDNF promoter increased BDNF mRNA. In additional studies, RGFP966, a pharmacological inhibitor of HDAC3, elevated BDNF expression and BRD4 binding to the BDNF promoter, effects that were abrogated by JQ1 (an inhibitor of BRD4). Examining known epigenetic targets of BRD4 and HDAC3, we show that H4K5ac and H4K8ac modifications and H4K5ac enrichment at the BDNF promoter were elevated following RGFP966 treatment. In electrophysiological studies, JQ1 reversed RGFP966-induced enhancement of LTP in hippocampal slice preparations. Last, in behavioral studies, RGFP966 increased subthreshold novel object recognition memory and cocaine place preference in male C57BL/6 mice, effects that were reversed by cotreatment with JQ1. Together, these data reveal that BRD4 plays a key role in HDAC3 inhibitor-induced potentiation of BDNF expression, neuroplasticity, and memory.SIGNIFICANCE STATEMENT Some histone deacetylase (HDAC) inhibitors are known to have neuroprotective and cognition-enhancing properties, but the underlying mechanisms have yet to be fully elucidated. In the current study, we reveal that BRD4, an epigenetic reader of histone acetylation marks, is necessary for enhancing brain-derived neurotrophic factor (BDNF) expression and improved memory following HDAC inhibition. Therefore, by identifying novel epigenetic regulators of BDNF expression, these data may lead to new therapeutic targets for the treatment of neuropsychiatric disorders.
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Fator Neurotrófico Derivado do Encéfalo/biossíntese , Inibidores de Histona Desacetilases/farmacologia , Memória/efeitos dos fármacos , Acrilamidas/farmacologia , Animais , Azepinas/farmacologia , Fator Neurotrófico Derivado do Encéfalo/efeitos dos fármacos , Epigênese Genética , Técnicas de Silenciamento de Genes , Histona Desacetilase 2/genética , Histona Desacetilase 2/metabolismo , Histona Desacetilases/genética , Histona Desacetilases/metabolismo , Potenciação de Longa Duração/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Proteínas Nucleares/antagonistas & inibidores , Proteínas Nucleares/genética , Fenilenodiaminas/farmacologia , Ratos , Fatores de Transcrição/antagonistas & inibidores , Fatores de Transcrição/genética , Triazóis/farmacologia , Vorinostat/farmacologiaRESUMO
Defective cholesterol metabolism primarily linked to reduced ATP-binding cassette transporter A1 (ABCA1) expression is closely associated with the pathogenesis and progression of kidney diseases, including diabetic kidney disease and Alport Syndrome. However, whether the accumulation of free or esterified cholesterol contributes to progression in kidney disease remains unclear. Here, we demonstrate that inhibition of sterol-O-acyltransferase-1 (SOAT1), the enzyme at the endoplasmic reticulum that converts free cholesterol to cholesterol esters, which are then stored in lipid droplets, effectively reduced cholesterol ester and lipid droplet formation in human podocytes. Furthermore, we found that inhibition of SOAT1 in podocytes reduced lipotoxicity-mediated podocyte injury in diabetic kidney disease and Alport Syndrome in association with increased ABCA1 expression and ABCA1-mediated cholesterol efflux. In vivo, Soat1 deficient mice did not develop albuminuria or mesangial expansion at 10-12 months of age. However, Soat1 deficiency/inhibition in experimental models of diabetic kidney disease and Alport Syndrome reduced cholesterol ester content in kidney cortices and protected from disease progression. Thus, targeting SOAT1-mediated cholesterol metabolism may represent a new therapeutic strategy to treat kidney disease in patients with diabetic kidney disease and Alport Syndrome, like that suggested for Alzheimer's disease and cancer treatments.
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Diabetes Mellitus , Nefropatias Diabéticas , Nefrite Hereditária , Podócitos , Albuminúria , Animais , Colesterol , Nefropatias Diabéticas/etiologia , Humanos , Camundongos , Nefrite Hereditária/genéticaRESUMO
Additional Sex Combs-Like 1 (ASXL1) is mutated at a high frequency in all forms of myeloid malignancies associated with poor prognosis. We generated a Vav1 promoter-driven Flag-Asxl1Y588X transgenic mouse model, Asxl1Y588X Tg, to express a truncated FLAG-ASXL1aa1-587 protein in the hematopoietic system. The Asxl1Y588X Tg mice had an enlarged hematopoietic stem cell (HSC) pool, shortened survival, and predisposition to a spectrum of myeloid malignancies, thereby recapitulating the characteristics of myeloid malignancy patients with ASXL1 mutations. ATAC- and RNA-sequencing analyses revealed that the ASXL1aa1-587 truncating protein expression results in more open chromatin in cKit+ cells compared with wild-type cells, accompanied by dysregulated expression of genes critical for HSC self-renewal and differentiation. Liquid chromatography-tandem mass spectrometry and coimmunoprecipitation experiments showed that ASXL1aa1-587 acquired an interaction with BRD4. An epigenetic drug screening demonstrated a hypersensitivity of Asxl1Y588X Tg bone marrow cells to BET bromodomain inhibitors. This study demonstrates that ASXL1aa1-587 plays a gain-of-function role in promoting myeloid malignancies. Our model provides a powerful platform to test therapeutic approaches of targeting the ASXL1 truncation mutations in myeloid malignancies.
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Mutação com Ganho de Função/genética , Leucemia Mieloide/genética , Proteínas Repressoras/genética , Animais , Células da Medula Óssea/metabolismo , Diferenciação Celular/genética , Linhagem da Célula/genética , Cromatina/metabolismo , Regulação Leucêmica da Expressão Gênica , Células-Tronco Hematopoéticas/metabolismo , Leucemia Mieloide/patologia , Camundongos Transgênicos , Proteínas Nucleares/metabolismo , Regiões Promotoras Genéticas/genética , Ligação Proteica , Proteínas Proto-Oncogênicas c-kit/metabolismo , Proteínas Proto-Oncogênicas c-vav/metabolismo , Fatores de Transcrição/metabolismoRESUMO
The mammalian target of rapamycin (mTOR) positively regulates axon growth in the mammalian central nervous system (CNS). Although axon regeneration and functional recovery from CNS injuries are typically limited, knockdown or deletion of PTEN, a negative regulator of mTOR, increases mTOR activity and induces robust axon growth and regeneration. It has been suggested that inhibition of S6 kinase 1 (S6K1, gene symbol: RPS6KB1), a prominent mTOR target, would blunt mTOR's positive effect on axon growth. In contrast to this expectation, we demonstrate that inhibition of S6K1 in CNS neurons promotes neurite outgrowth in vitro by twofold to threefold. Biochemical analysis revealed that an mTOR-dependent induction of PI3K signaling is involved in mediating this effect of S6K1 inhibition. Importantly, treating female mice in vivo with PF-4708671, a selective S6K1 inhibitor, stimulated corticospinal tract regeneration across a dorsal spinal hemisection between the cervical 5 and 6 cord segments (C5/C6), increasing axon counts for at least 3 mm beyond the injury site at 8 weeks after injury. Concomitantly, treatment with PF-4708671 produced significant locomotor recovery. Pharmacological targeting of S6K1 may therefore constitute an attractive strategy for promoting axon regeneration following CNS injury, especially given that S6K1 inhibitors are being assessed in clinical trials for nononcological indications.SIGNIFICANCE STATEMENT Despite mTOR's well-established function in promoting axon regeneration, the role of its downstream target, S6 kinase 1 (S6K1), has been unclear. We used cellular assays with primary neurons to demonstrate that S6K1 is a negative regulator of neurite outgrowth, and a spinal cord injury model to show that it is a viable pharmacological target for inducing axon regeneration. We provide mechanistic evidence that S6K1's negative feedback to PI3K signaling is involved in axon growth inhibition, and show that phosphorylation of S6K1 is a more appropriate regeneration indicator than is S6 phosphorylation.
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Axônios/metabolismo , Imidazóis/administração & dosagem , Piperazinas/administração & dosagem , Proteínas Quinases S6 Ribossômicas 90-kDa/metabolismo , Traumatismos da Medula Espinal/tratamento farmacológico , Traumatismos da Medula Espinal/enzimologia , Regeneração da Medula Espinal/efeitos dos fármacos , Serina-Treonina Quinases TOR/metabolismo , Animais , Células Cultivadas , Sistemas de Liberação de Medicamentos , Regulação Enzimológica da Expressão Gênica/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Terapia de Alvo Molecular , Crescimento Neuronal/efeitos dos fármacos , Ligação Proteica , Proteínas Quinases S6 Ribossômicas 90-kDa/antagonistas & inibidores , Especificidade por Substrato , Resultado do TratamentoRESUMO
OBJECTIVE: To describe the natural history and outcomes of surveillance of duodenal neoplasia in familial adenomatous polyposis (FAP). BACKGROUND: Duodenal cancer is the most common cause of death in FAP. METHODS: Cohort study of patients prospectively enrolled in an upper endoscopic surveillance protocol from 1982 to 2012. The duodenum was assessed by side-viewing endoscopy and classified as stage 1 to 5 disease. Endoscopic and/or operative interventions were performed according to stage. RESULTS: There were 218 patients in the protocol (98 with advanced stage). They had a median of 9 endoscopies (range: 2-25) over a median of 11 years (range: 1-26). Median age at diagnosis of stage 3 disease (adenoma: 2.1-10 mm) was 41 years and stage 4 disease (adenoma >10 mm) was 45 years. Median time from first esophagogastroduodenoscopy to stage 4 disease was 22.4 years. The risk of stage 4 disease was 34.3% [95% confidence interval (CI) 23.8-43.4] at 15 years. In multivariate analysis, sex, type of colorectal surgery, years since colorectal surgery, and stage were significantly associated with risk of progression to stage 4 disease. Five of 218 (2.3%) patients developed duodenal cancer at median age of 58 years (range: 51-65). The risk of developing duodenal cancer was 2.1% (95% CI: 0-5.2) at 15 years. CONCLUSIONS: Patients with advanced duodenal polyposis progress in the severity of disease (size and degree of dysplasia); however, the rate of progression to carcinoma is slow. Aggressive endoscopic and surgical intervention, especially in the presence of large polyps and high-grade dysplasia, appears to be effective in preventing cancer deaths in FAP.
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Adenoma/diagnóstico , Polipose Adenomatosa do Colo/diagnóstico , Neoplasias Duodenais/diagnóstico , Adenoma/etiologia , Adenoma/cirurgia , Polipose Adenomatosa do Colo/complicações , Adulto , Idoso , Protocolos Clínicos , Gerenciamento Clínico , Progressão da Doença , Neoplasias Duodenais/classificação , Neoplasias Duodenais/etiologia , Neoplasias Duodenais/cirurgia , Duodenoscopia , Detecção Precoce de Câncer , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Vigilância da População , Estudos Prospectivos , Sistema de Registros , Fatores de RiscoRESUMO
CONTEXT: Solid pseudopapillary tumors (SPT) are rare, generally low grade pancreatic neoplasms that occasionally display malignant behavior. OBJECTIVE: To analyze the clinical and pathological features associated with increased risk of recurrence of SPT. METHODS: Cohort study of patients with SPT who underwent resection of the primary tumor and in selected cases resection of metastatic disease from 1999-2013 at a single tertiary care Hepatopancreatobiliary center. Risk factors for recurrence were statistically analyzed. RESULTS: There were 32 patients. The mean age was 35.65 years (standard deviation: 12.26), 26/32, 81.25% were female. Median size of resected tumors was 4.7 cm (1.1-14.5). Most were solid and cystic (22/32, 68.75%), encapsulated (27/32, 84.4%) and located in the pancreatic body or tail (22/32, 68.75%). All displayed strong ß-catenin, cyclin D1, CD56, and progesterone receptor staining with loss of E-cadherin. Most stained positive for vimentin (15/16, 93.75%) and CD10 (17/18, 94.4%). Median follow-up was 43 months (range: 3-207); 3/32, 9.38% recurred (all after 5-years from curative resection) and 1 died by the end of the study period, 11 years after diagnosis. Patients who developed recurrences (n=3) more commonly had synchronous metastases at presentation (P=0.006), lymphovascular invasion (P=0.04) and invasion of tumor capsule (P=0.08) compared to those who did not have disease recurrence. CONCLUSIONS: Lymphovascular invasion, synchronous metastases and local invasion of tumor capsule are associated with aggressive behavior. Since recurrences may occur >5 years from resection, this high-risk group should undergo extended follow-up. Progression and recurrence is slow, therefore, resection of liver metastases can offer long-term survival.
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BACKGROUND: Hepatic metastasis from colorectal cancer (CRC) is best managed with a multimodal approach; however, the optimal timing of liver resection in relation to administration of perioperative chemotherapy remains unclear. Our strategy has been to offer up-front liver resection for patients with resectable hepatic metastases, followed by post-liver resection chemotherapy. We report the outcomes of patients based on this surgical approach. METHODS: A retrospective review of all patients undergoing liver resection for CRC metastases over a 5-year period (2002-2007) was performed. Associations between clinicopathologic factors and survival were evaluated by the Cox proportional hazard method. RESULTS: A total of 320 patients underwent 336 liver resections. Median follow-up was 40 (range 8-80) months. The majority (n=195, 60.9%) had metachronous disease, and most patients (n=286, 85%) had a major hepatectomy (>3 segments). Thirty-six patients (11%) received preoperative chemotherapy, predominantly for downstaging unresectable disease. Ninety-day mortality was 2.1%, and perioperative morbidity occurred in 68 patients (20.2%). Actual disease-free survival at 3 and 5 years was 46.2% and 42%, respectively. Actual overall survival (OS) at 3 and 5 years was 63.7% and 55%, respectively. Multivariate analysis identified four factors that were independently associated with differences in OS (hazard ratio; 95% confidence interval): size of metastasis>6 cm (2.2; 1.3-3.5), positive lymph node status of the primary CRC (N1 (2.0; 1.0-3.8), N2 (2.4; 1.2-4.9)), synchronous disease (2.1; 1.3-3.5), and treatment with chemotherapy after liver resection (0.42; 0.23-0.75). CONCLUSIONS: Up-front surgery for patients with resectable CRC liver metastases, followed by chemotherapy, can lead to favorable OS.
Assuntos
Antineoplásicos/uso terapêutico , Neoplasias Colorretais/patologia , Hepatectomia , Neoplasias Hepáticas/terapia , Adulto , Idoso , Idoso de 80 Anos ou mais , Quimioterapia Adjuvante , Intervalo Livre de Doença , Feminino , Hepatectomia/efeitos adversos , Humanos , Estimativa de Kaplan-Meier , Neoplasias Hepáticas/patologia , Neoplasias Hepáticas/secundário , Metástase Linfática , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Neoplasia Residual , Modelos de Riscos Proporcionais , Estudos Retrospectivos , Fatores de Tempo , Adulto JovemRESUMO
Lipid droplets (LDs), initially thought to be mere lipid storage structures, are highly dynamic organelles with complex functions that control cell fate and behavior. In recent years, their relevance as therapeutic targets for a wide array of human diseases has been well established. Consequently, efforts to develop tools to study them have intensified, including assays that can accurately track LD levels in clinically relevant cell-based models. We previously reported that LD accumulation destines podocytes for lipotoxicity and cell death in renal diseases of metabolic and nonmetabolic origin. We also showed that LD accumulation in those cells serves as both a marker for disease progression and as a therapeutic target. Here, we describe a robust phenotypic screening method, using differentiated human podocytes, for identifying small-molecule compounds that rescue podocytes from LD accumulation and lipotoxicity under cellular stress. Major assay advances include 1) the use of a solvatochromic dye to improve LD staining, reduce background noise, and improve detection accuracy, 2) use of confocal imaging to reduce vertical overlap of LDs and enable accurate counting, 3) combining membrane and cytoskeleton stains to improve cell segmentation in confocal mode, and 4) use of an optimized spot detection algorithm that requires minimal configuration per individual run. The assay is robust and yields a Z-factor that is consistently >0.5.
Assuntos
Nefropatias , Podócitos , Humanos , Gotículas Lipídicas/metabolismo , Podócitos/metabolismo , Diferenciação Celular , Nefropatias/metabolismo , Metabolismo dos LipídeosRESUMO
Sodium-glucose cotransporter-2 inhibitors (SGLT2i) are anti-hyperglycemic agents that prevent glucose reabsorption in proximal tubular cells. SGLT2i improves renal outcomes in both diabetic and non-diabetic patients, indicating it may have beneficial effects beyond glycemic control. Here, we demonstrate that SGLT2i affects energy metabolism and podocyte lipotoxicity in experimental Alport syndrome (AS). In vitro, we found that the SGLT2 protein was expressed in human and mouse podocytes to a similar extent in tubular cells. Newly established immortalized podocytes from Col4a3 knockout mice (AS podocytes) accumulate lipid droplets along with increased apoptosis when compared to wild-type podocytes. Treatment with SGLT2i empagliflozin reduces lipid droplet accumulation and apoptosis in AS podocytes. Empagliflozin inhibits the utilization of glucose/pyruvate as a metabolic substrate in AS podocytes but not in AS tubular cells. In vivo, we demonstrate that empagliflozin reduces albuminuria and prolongs the survival of AS mice. Empagliflozin-treated AS mice show decreased serum blood urea nitrogen and creatinine levels in association with reduced triglyceride and cholesterol ester content in kidney cortices when compared to AS mice. Lipid accumulation in kidney cortices correlates with a decline in renal function. In summary, empagliflozin reduces podocyte lipotoxicity and improves kidney function in experimental AS in association with the energy substrates switch from glucose to fatty acids in podocytes.
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Diabetes Mellitus Tipo 2 , Nefrite Hereditária , Podócitos , Inibidores do Transportador 2 de Sódio-Glicose , Humanos , Camundongos , Animais , Podócitos/metabolismo , Nefrite Hereditária/tratamento farmacológico , Nefrite Hereditária/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Inibidores do Transportador 2 de Sódio-Glicose/farmacologia , Inibidores do Transportador 2 de Sódio-Glicose/metabolismo , Glucose/toxicidade , Glucose/metabolismoRESUMO
The use of inhibitors of epigenetic modifiers in the treatment of acute myeloid leukemia (AML) has become increasingly appealing due to the highly epigenetic nature of the disease. We evaluated a library of 164 epigenetic compounds in a cohort of 9 heterogeneous AML patients using an ex vivo drug screen. AML blasts were isolated from bone marrow biopsies according to established protocols and treatment response to the epigenetic library was evaluated. We find that 11 histone deacetylase (HDAC) inhibitors, which act upon mechanisms of cell cycle arrest and apoptotic pathways through inhibition of zinc-dependent classes of HDACs, showed efficacy in all patient-derived samples. Other compounds, including bromodomain and extraterminal domain (BET) protein inhibitors, showed efficacy in most samples. Specifically, HDAC inhibitors are already clinically available and can be repurposed for use in AML. Results in this cohort of AML patient-derived samples reveal several epigenetic compounds with high anti-blast activity in all samples, despite the molecular diversity of the disease. These results further enforce the notion that AML is a predominantly epigenetic disease and that similar epigenetic mechanisms may underlie disease development and progression in all patients, despite differences in genetic mutations.
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Gastric cancer (GC) is frequently characterized by resistance to standard chemotherapeutic regimens and poor clinical outcomes. We aimed to identify a novel therapeutic approach using drug sensitivity testing (DST) and our computational SynerySeq pipeline. DST of GC cell lines was performed with a library of 215 Federal Drug Administration (FDA) approved compounds and identified clofarabine as a potential therapeutic agent. RNA-sequencing (RNAseq) of clofarabine treated GC cells was analyzed according to our SynergySeq pipeline and identified pictilisib as a potential synergistic agent. Clonogenic survival and Annexin V assays demonstrated increased cell death with clofarabine and pictilisib combination treatment (P<0.01). The combination induced double strand breaks (DSB) as indicated by phosphorylated H2A histone family member X (γH2AX) immunofluorescence and western blot analysis (P<0.01). Pictilisib treatment inhibited the protein kinase B (AKT) cell survival pathway and promoted a pro-apoptotic phenotype as evidenced by quantitative real time polymerase chain reaction (qRT-PCR) analysis of the B-cell lymphoma 2 (BCL2) protein family members (P<0.01). Patient derived xenograft (PDX) data confirmed that the combination is more effective in abrogating tumor growth with prolonged survival than single-agent treatment (P<0.01). The novel combination of clofarabine and pictilisib in GC promotes DNA damage and inhibits key cell survival pathways to induce cell death beyond single-agent treatment.
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Recovery from spinal cord injury (SCI) and other central nervous system (CNS) trauma is hampered by limits on axonal regeneration in the CNS. Regeneration is restricted by the lack of neuron-intrinsic regenerative capacity and by the repressive microenvironment confronting damaged axons. To address this challenge, we have developed a therapeutic strategy that co-targets kinases involved in both extrinsic and intrinsic regulatory pathways. Prior work identified a kinase inhibitor (RO48) with advantageous polypharmacology (co-inhibition of targets including ROCK2 and S6K1), which promoted CNS axon growth in vitro and corticospinal tract (CST) sprouting in a mouse pyramidotomy model. We now show that RO48 promotes neurite growth from sensory neurons and a variety of CNS neurons in vitro, and promotes CST sprouting and/or regeneration in multiple mouse models of spinal cord injury. Notably, these in vivo effects of RO48 were seen in several independent experimental series performed in distinct laboratories at different times. Finally, in a cervical dorsal hemisection model, RO48 not only promoted growth of CST axons beyond the lesion, but also improved behavioral recovery in the rotarod, gridwalk, and pellet retrieval tasks. Our results provide strong evidence for RO48 as an effective compound to promote axon growth and regeneration. Further, they point to strategies for increasing robustness of interventions in pre-clinical models.
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Axônios , Traumatismos da Medula Espinal , Animais , Axônios/patologia , Modelos Animais de Doenças , Camundongos , Regeneração Nervosa/fisiologia , Neurônios/metabolismo , Tratos Piramidais/patologia , Recuperação de Função Fisiológica/fisiologia , Medula Espinal/patologia , Traumatismos da Medula Espinal/patologiaRESUMO
Mitochondrial copper metabolism and delivery to cytochrome c oxidase and mitochondrially localized CuZn-superoxide dismutase (Sod1) requires a growing number of intermembrane space proteins containing a twin Cx(9)C motif. Among them, Cmc1 was recently identified by our group. Here we describe another conserved mitochondrial metallochaperone-like protein, Cmc2, a close homologue of Cmc1, whose function affects both cytochrome c oxidase and Sod1. In the yeast Saccharomyces cerevisiae, Cmc2 localizes to the mitochondrial inner membrane facing the intermembrane space. In the absence of Cmc2, cytochrome c oxidase activity measured spectrophotometrically and cellular respiration measured polarographically are undetectable. Additionally, mutant cmc2 cells display 2-fold increased mitochondrial Sod1 activity, whereas CMC2 overexpression results in Sod1 activity decreased to 60% of wild-type levels. CMC1 overexpression does not rescue the respiratory defect of cmc2 mutants or vice versa. However, Cmc2 physically interacts with Cmc1 and the absence of Cmc2 induces a 5-fold increase in Cmc1 accumulation in the mitochondrial membranes. Cmc2 function is conserved from yeast to humans. Human CMC2 localizes to the mitochondria and CMC2 expression knockdown produces cytochrome c oxidase deficiency in Caenorhabditis elegans. We conclude that Cmc1 and Cmc2 have cooperative but nonoverlapping functions in cytochrome c oxidase biogenesis.
Assuntos
Complexo IV da Cadeia de Transporte de Elétrons/biossíntese , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Sequência de Aminoácidos , Sequência de Bases , Sequência Conservada , Primers do DNA , Dados de Sequência Molecular , Interferência de RNA , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Saccharomyces cerevisiae/enzimologia , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/imunologia , Homologia de Sequência de AminoácidosRESUMO
After injury to the central nervous system (CNS), both neuron-intrinsic limitations on regenerative responses and inhibitory factors in the injured CNS environment restrict regenerative axon growth. Instances of successful axon regrowth offer opportunities to identify features that differentiate these situations from that of the normal adult CNS. One such opportunity is provided by the kinase inhibitor RO48, which dramatically enhances neurite outgrowth of neurons in vitro and substantially increased contralateral sprouting of corticospinal tract neurons when infused intraventricularly following unilateral pyramidotomy. The authors present here a transcriptomic deconvolution of RO48-associated axon growth, with the goal of identifying transcriptional regulators associated with axon growth in the CNS. Through the use of RNA sequencing (RNA-seq) and transcription factor binding site enrichment analysis, the authors identified a list of transcription factors putatively driving differential gene expression during RO48-induced neurite outgrowth of rat hippocampal neurons in vitro. The 82 transcription factor motifs identified in this way included some with known association to axon growth regulation, such as Jun, Klf4, Myc, Atf4, Stat3, and Nfatc2, and many with no known association to axon growth. A phenotypic loss-of-function screen was carried out to evaluate these transcription factors for their roles in neurite outgrowth; this screen identified several potential outgrowth regulators. Subsequent validation suggests that the Forkhead box (Fox) family transcription factor Foxp2 restricts neurite outgrowth, while FoxO subfamily members Foxo1 and Foxo3a promote neurite outgrowth. The authors' combined transcriptomic-phenotypic screening strategy therefore allowed identification of novel transcriptional regulators of neurite outgrowth downstream of a multitarget kinase inhibitor.
Assuntos
Axônios/efeitos dos fármacos , Crescimento Neuronal/efeitos dos fármacos , Inibidores de Proteínas Quinases/farmacologia , Fatores de Transcrição/genética , Transcriptoma/efeitos dos fármacos , Animais , Sistema Nervoso Central/efeitos dos fármacos , Sistema Nervoso Central/fisiologia , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica/genética , Neuritos/efeitos dos fármacos , Neuritos/fisiologia , Crescimento Neuronal/genética , Neurônios/efeitos dos fármacos , Neurônios/fisiologia , Ratos , Ratos Sprague-Dawley , Transcriptoma/genéticaRESUMO
BACKGROUND: Discoidin domain receptor 1 (DDR1) is a receptor tyrosine kinase that is activated by collagens that is involved in the pathogenesis of fibrotic disorders. Interestingly, de novo production of the collagen type I (Col I) has been observed in Col4a3 knockout mice, a mouse model of Alport Syndrome (AS mice). Deletion of the DDR1 in AS mice was shown to improve survival and renal function. However, the mechanisms driving DDR1-dependent fibrosis remain largely unknown. METHODS: Podocyte pDDR1 levels, Collagen and cluster of differentiation 36 (CD36) expression was analyzed by Real-time PCR and Western blot. Lipid droplet accumulation and content was determined using Bodipy staining and enzymatic analysis. CD36 and DDR1 interaction was determined by co-immunoprecipitation. Creatinine, BUN, albuminuria, lipid content, and histological and morphological assessment of kidneys harvested from AS mice treated with Ezetimibe and/or Ramipril or vehicle was performed. FINDINGS: We demonstrate that Col I-mediated DDR1 activation induces CD36-mediated podocyte lipotoxic injury. We show that Ezetimibe interferes with the CD36/DDR1 interaction in vitro and prevents lipotoxicity in AS mice thus preserving renal function similarly to ramipril. INTERPRETATION: Our study suggests that Col I/DDR1-mediated lipotoxicity contributes to renal failure in AS and that targeting this pathway may represent a new therapeutic strategy for patients with AS and with chronic kidney diseases (CKD) associated with Col4 mutations. FUNDING: This study is supported by the NIH grants R01DK117599, R01DK104753, R01CA227493, U54DK083912, UM1DK100846, U01DK116101, UL1TR000460 (Miami Clinical Translational Science Institute, National Center for Advancing Translational Sciences and the National Institute on Minority Health and Health Disparities), F32DK115109, Hoffmann-La Roche and Alport Syndrome Foundation.